US1041529A - Means for regulating centrifugal compressors. - Google Patents

Description

RTEUGER.

MEANS FOR REGULATING GENTRIFUGAL GOMPRESSORS.

, APPLIUATION IILI EID FEB. 16, 19 12. 1,041,529.

Patented Oct. 15, 1912.

Inventor,

Witnesses;

lQichar-cl To all u'howz'. it may concern:

Be it known that I, RICHARD Trotter, a

RICHARD TRGGER, F CHARLOTTENBUBG, GERMANY, ASSIGEOB/ 'iO GENERAL ELECTRIC COMPAHY, A CORPGBATION OF NEW YGBK.

MEANS FOR nneULATrNG onnrnrruo'an ooiltrnnssoits.

Specification oi Letters Patent.

Application'filed February 16, 1912. Serial No. 673,923.

subject of the King of-Prussia, residing at Charlottenburg, Germany, have invented certain new and" useful Improvements in Means for Regulating Centrifugal Compressors, of which the following is a specification.

In the operationof centrifugal air compressors when the load is decreased to a small percentage of the total, a peculiar ac tion known as surging or pumping takes place, meaning thereby that the air surges to and fro in the compressor and in the pipingconnected thereto. For the purpose of this case it is suflioient to say that surging is highly objectionable as it causes excessive .vibration and noise,.inte rferes with the operation of the apparatus supplied with 'air,'

and decreases the economy of operation. It has been proposed to prevent surging by placing a blow-oft valve in-the discharge conduit that is' set to open automatically when thevolun'ie of air discharged by the,

compressor reaches a certain. relatively small value, said valve operating in res spouse to a pressure difference-existing be tween two points in the discharge conduit. Since the valve always opens when the load decreases to said predetermined-low or criti-v cal value, it'follows that as the load is further decreased the energy required to drive the compressor will remain the same, be cause the amount of air passingthrough the compressor will remain the same, butthe amount of air discharged or escaping through the valve will, however, increaseas the load decreases. In other words, these compressors are inefiicient and wasteful-at light loads.

the present invention has for its object to provide .an improved goi'erning or regulating mechanism for compressors, whereby their effective and efilcient range of opera tion can be increased, especially at. light loads. and the losses decreased. 7

In carrying-out my invention a blow-oh valve is placed in the discharge conduit of .the compressor but instead ofbeing responsive to. a pressure ditlerenceexistin'g on the discharge side of the compressor as heretofore, itis responsive to apressure diiterence existing on the-inlet side. This pressure difference is obtained through. the use of a suitable device such as Venturi tube, one side that said pressure difference due to the action of the tube must bear a definite relation to-the volume air passing into-the compressor; By means of the throttle valve, I can vary the output of the compressor over wide limits, and at the same time the criti-' cal point-of opening of the blow-ofl' vulve will be lowered as the lead. is decreased thereby decreasing the losses heretofore mentioned. "To state the matter another. way, my invention comprises the feature that the pressure difference acting upon the blow-oil valve obtained from the part of the suction conduit of the coi'npressor which follows a throttling member, so that the pressure difference which is critical for the opening of the blow-oil'walvc is made to depend upon the suction-pressure as regulated by'the throttling member.

In the accompanying drawing, which illustrates one of the/embodiments of my invention, is shown a multistage centrifugal air compressor and the regulating mechanism therefor.

1 indicates a multistage centrifugal air compressor of any suitable type. It driven by a motor 2 shown in dotted lines,

which may be an electric motor a st am The compressor;

pipe 8 that leads to the motor'for actuating the blow-off valve as will appear later. 9 indicates a pipe connected to the inlet conduit at or about the discharge end of the tube. This also conveys fluidunder pressure'to the motor for actuating the blowpfi valvef Between the throat-6 and the end of the tube a pres'sure ditlerence exists when air or other fluid is tlowingthrough the inlet conduit.- This pressure lgliiiierence will depend upon the amount of fluid flowing, it'

Patentedflct, 15,1912.

being greater as the amount of fluid in creases. The pressure existing at the throat 6 will be less than that existing at the dis-' the throttling effect of thevalve 10 can be adjusted. a

4 The construction and arrangement of the blow-ofl valve will now be described: Connected to the discharge conduit tor formed integral therewith is a c linder 14 containing a piston valve 15, t e latter being arranged to move up and down to cover and uncover the discharge ports 16 shown -.in

dotted lines. The valve is actuated by a piston ;17 located in the enlarged cylinder 18. Between the upper side of the piston.-

and the head of the cylinder is located a compression spring 19 that normally tends to push the valve 15 downward and open the orts 16 and permit air to escape. This tenciency is opposed by the pressure differ .ence created by the device. located in the inlet conduit, 2'. e., the Venturi tube.

In 'rrderto-balance the pressures on opposite sides of the valve 15, a bypass 20 is provided that connects the conduit 4 with the cylinderl t.

The fluid pressure above the piston 17 is less. than the fluid pressure 'below it. So long as the compressor is working above a certain minimum load, the fluid pressure under the piston 17 will be suflicient to overcome the effect of the fluid pressure received from the pipe 8 and the force exerted by the spring 19, but when the load is decreased to such a'low value that surging could take place, the pressure difieren'ce due to the Venturi tube decreases, so'that the pressure of the spring 19 when added to that of the fluid received from the pipe 8 .will be sufli-.;

cient to open the valve '15, and discharge air through the ports 16. It will thus be seen that the valve 15 forms a means for insuring a certain minimum load for the com pressor and its driving motor, which load is superior to that at which surging can take place. Furthermore, since the throttle valve precedes the device for creating pressure difference it follows that the latter is under the control of said valve. Such being the case, the blow-off valve'instead of opening at all times un'der-the same load conditions, will open at' different load conditions depending u on the throttling efifect n other words, the range of the .valve 10;

of operation of the-compressor can be increased by my improved arrangement, owing to the fact that the blow-off valve is not set for onefixedminimlun load, but is-set to operate at an infinite number of load values, dependingupon the position of the throttle valve. Assuming the compressor to be in service and that the consumption of compressed air decreases for any cause, the throttle valve being wide. open. With the decrease in consumption, the pressure difference act-ing on the valve 15 correspondingly decreases and at' a certain minimum work performance of the compressor, the blow-off valve will open and discharge air. The operator on observing this fact, can, by throttling the inlet conduit, reduce the work performance ofthe compressor within certain limits I without, however, causing surging, and at 85, the same time the further opening of the blow-off valve will be retarded depending upon'the degree of throttling.

In accordance with the provisions of the "patent st atutes, I have described the principle of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof; but

I desireto have it understood that the apparatus shown is only illustrative, and that the inventioncan be carried out by other means. What I claim as new and desire to secure I by Letters Iatent of the United States, is .1. In combination, a' centrifugal com J."

ressor having an inlet and a discharge consuit, a blow-ofl' valve for discharging fluidunder pressure from I the compressor, a throttle valve in the inlet, and a means lo- 'cated on "the compressor side of the'throttle and sensitive to a change in the rate of flow of fl'ui passing through it for actuating the blow-oft valve.

2. Incombination, a centrifugal comressor having an inlet and a discharge conuit, a 'bloW-ofi' valve in the discharge mm duit, a means sensitive to, a change, in the rate of flow of fluid passing through the in- .let for controlling the operation of the .blowoil'- valve, and a memberfor throttling the passageof fluid prior to its entrance to the 5 inlet and said means' j 3. In combination, a centrifugal comressor having an inletand a discharge consuit,- a blow-ofl' valve in the discharge conduit, a-means located in the inlet for creat- 2 ing a ressure difference responsive to changes In the rate of flow of the fluid passing through the compressor, a means for actuating the blow-off valve that is responsive to sai pressure difierence, and a throttle valve that is located in the inlet and precedes the said means. 4.1a combination, a centrifugal compressor] having. an inlet and a discharge conduit, ablow-ofi .valve in the discharge '1,04 1,529 p p i 3 conduit, means tending at allftimes to open and athrottle valve that is located on-the inlet side of said device.

In combination, a cont-rifugal compressor having an inlet and a discharge coniluit, a blow-off valve in the discharge con :Iuit. that is arranged to open when the load 0;; the compressor falls below a certain value. a means actuated by fluid under-pressure for holding the valve closed, a Venturi tuhefor creatmg a pressure dlfference, condu ts conveying fluld under pressure from the tube to the'saidmeans, and a throttle valve in the inlet conduit for controlling the amount of fluid that passes through said 20 tube.

6. In combination, a centrifugal compressor having anmlet and a dlscharge con- .duit, a blow-oft" valve inthe discharge conduit that opens under conditions ofdecreas, 25 mg load, a Venturi tube in the inlet conduit for controlling the action of the valve, and a throttle valve that regulates the admission of fluid to said tube Inwitness whereof, I have hereunto set 30 my hand this dayof26th January, 1912. RICHARD TRoeER. Vitnesses:

JULIUS RIENLAND, OSKAR SINGER-A Copies of this patent may be obtained for five cents each, by addressing the. Commissioner of Patents,

' a Washington, D. C. i

Images